Electroplating apparatus



March 3, 1959 R. J, BACFIMAN $376,191

I ELECTROPLATYING APPARATUS Filed Sept. 5. 1952 lNl/EN TOR R. J. BACHMANATTORNEY ELECTROPLATING APPARATUS Robert J. Bachman, Towson, Md.,assignor to Western Electric Company, Incorporated, New York, N. Y., acorporation of New York Application September 5, 1952, Serial No.307,964

4 Claims. (Cl. 204-207) This invention relates to electroplatingapparatus, and more particularly to apparatus for electroplating movingwires.

Electrical conductors composed of copper-clad steel may be manufacturedadvantageously by electrodepositing heavy coatings of copper upon movingsteel wires. A great many steel wires may be advanced simultaneously inparallel, side-by-side relationship through a series of electrolyticcells in which anodically charged copper electrodes are located. Inbetween adjacent cells cathodically charged rolls may be provided toelectrically contact the moving-wires and to position and guide thewires in their passage through the series of cells.

In order to insure a reliable and highly conductive electrical contactbetween the rolls and the advancing wires, it has heretofore beenconsidered necessary to place a pair of staggered contact rolls in theair space between adjacent cells. These pairs of rolls have beenarranged so that the wires advance in a zigzag path under one roll andover the other. When such system is operated continuously over longperiods of time, it has been found that the rolls require frequentrepairs. The peripheral surfaces of the rolls that contact the movingwires may become Worn excessively. Furthermore, since the electricallycharged rolls inevitably become wetted by electrolyte clinging to themoving wires, metal may be deposited upon or removed from the peripheryof the rolls, depending upon operating conditions. Under suchcircumstances, the labor and expense of maintaining the rolls is atleast twice as burdensome as it would be in a satisfactory systemrequiring only a single contact roll between adjacent tanks.

An object of the invention is to provide new and improved electroplatingapparatus.

Another object of the invention is to provide new and improved apparatusfor electroplating moving wires.

An apparatus illustrating certain features of the invention may includea series of electrolytic cells aligned in tandem and alternately tiltedin opposite directions' A complete understanding of the invention may behad from the following detailed description of electro- "ice I pluralityof anodically charged plates 18-18 are immersed in the electrolyte inthe cells and are covered with a layer 19 of copper particles, whichgradually pass into solution to replenish the supply of metal ions inthe electrolyte as the plating process progresses. The plates 18-18extend along and are parallel to the bottoms of the cells.

In one suitable type of distribution system, electrolyte may beintroduced into the cells 12, 13, 14, and 16 through a plurality ofsupply pipes 20-20 which com- T municate with a plurality ofdistributors 21-21 having transverse cavities 22-22 therein. Theelectrolyte enters the cells through a plurality of orifices 24-24 whichbranch off from the cavities 22-22 and are designed to directthe'incoming solution so that it will flow parallel to the path traveledby the wires 10-10. If desired,

the number of orifices 24-24 may equal the number of wires 10-10, andone orifice may be located directly below each moving wire.

The distributors 21-21 may be molded from hard rubber, or other suitablecorrosion resistant material.

Similarly, the sides and bottoms of the several cells may be lined witha corrosion resistant material such as rubber. The tops of thedistributors are formed in the shape of weirs 25-25, which are slottedto permit passage therethrough of the wires 10-10 while minimizing theamount of electrolyte which may overflow from the cells. In a likemanner, the ends of the cells opposite the ends in which thedistributors are located are provided with weirs 26-26. Electrolyte mayoverflow from the opposite ends-of each cell, be collected in troughs(not shown),

plating apparatus forming a specific embodiment thereof,

when read in conjunction with the appended drawing, in which:

Fig. 1 is a fragmentary side elevation of an electroplating apparatusembodying the'invention, with portions thereof shown in section, and

,Fig. 2 is a fragmentary plan view looking at that portion of theapparatus beneath the line 2-2 of Fig. 1.

A plurality of steel wires 10-10 may be advanced in parallel,side-by-side relationship through a series of individual, equallyspaced, electroplating cells aligned in tandem, of which cells 12, 13,14, 15 and.16 are shown, from right to left as viewed in Fig. 1. Thesecells contain an electrolyte, such as a suitable copper sulfate andsulfuric acid solution, from which a thick layer of metallic copper iselectrodeposited onto the moving wires. A

and be recirculated back into the cells through the supply pipes 20-20.Cells embodying electrolyte distributors and weirs of this type areclaimed and described fully in copending application Serial No. 254,989,now' Patent No. 2,737,487, filed November 6, 1951, by V. A.Rayburn, forElectrolytic Apparatus. Y

, In accordance with the present invention, throughout the series ofcells a single cathodically charged roll is positioned between adjacentcells in each instance, and similar rolls are positioned at each end ofthe entire series of cells. Thus, a roll 28 is located between the cells12 and 13, a roll 29 is present between the cells 13 and 14, a roll 30lies between the cells 14 and 15, and a roll 31 is mounted between thecells 15 and 16. The elevation of these rollsis uniformly staggered sothat successive rolls are positioned at equal distances alternatelyabove and below the path of the wires. Thus, the wires 10-10 pass underthe roll 28, over the roll 29, then under the roll 30, and finally overthe roll 31, as the advancing wires successively contact the rolls inthe order named. Each .of the rolls is mounted rotatably on a pair ofvertical walls 32-32 erected on transversely opposite sides of the cellsperpendicular to a horizontal platform 34 on which all of the cells aresupported. The walls 32-32 also support driving means (not shown) forpositively rotating the rolls. Encircling the periphery of each roll area plurality of equally spaced grooves 36-36 designed to receive theadvancing wires 10-10. Obviously, the grooves on each roll are alignedproperly with the grooves oneach of the other rolls in order to guidethe wires in parallel lines during their passage through the series ofcells.

An important feature of the invention is the fact that posite directionsat equal angles above the horizontal.

Thus, the cell 12 is inclined so that the wires 10-10 enter this cell ata higher elevation than that at which the wires emerge from this cell.The next cell, cell' 13, is arranged to have its entrance end at thesame level as the exitend of the cell 12. From this point, the

wardly. The portions'of the wires that extend from the bottom of theroll 28-to the top of the roll 29 are perfectly straight, with a slightupward inclination from right to left as viewedin Fig. 1. Similarly, thepath of the wires between each of the other rolls is straight. As aresult of the alternate opposite inclination of successive straightportions of the path of the wires, their path as a whole is a zigzag.

Each straight portion of the zigzag path of the wires -10 travelsparallel to one of the anodically charged plates 18-18 and perpendicularto the end walls of the cellin which this plate lies, so that the wiresremain equidistantly spaced from the anodes as they progress through theseries of cells submerged in the electrolyte. The moving wires areneither positively rotated nor are they prevented from rotating, but itwill be observed in practice that they tend naturally to rotate andoscillate as they pass through different portions of the series ofcells. Perhaps this is because even slight variations in thetstraightnessor the longitudinal, tension of a round wire may cause thewire to creep up the walls of a groove on. a contact roll. Although theanode plates 18-18 are located on only one side of the path of thewires, the natural rotation and oscillation of the wires causes allsides of the wires to face the cathode plates for about the same lengthof time.' As a result, when wires are advanced through a series of cellsof sufi'icient length for this tendency to rotate and oscillate tomanifest itself, it is not necessary to surround the wires with anodicplates to insure that all surfaces of the wires will be equidistantlyspaced from the anodes.

I Theuniform staggering of the elevation of therolls is so'arranged thatsuccessive rolls are positioned equal distances alternately aboveandbelow the advancing wires 10-10. In order to achieve the zigzag patternof the passage of the wires through the entire series of cells, thebottomsof 'all of'the upper rolls protrude equal disstances slightlybelow the horizontal plane in which all of the tops of the bottom rollslie. In following its zigzag motion, each wire is bent slightly aroundeach roll so as to provide an elongated, curved area of contact,:instead of a tangential contact at one point on the periphery of aroll. As the wires bend around the rolls, contact is made withlpressureagainst the rolls, thereby insuring that the wires can be positivelydriven by the rolls while making good electrical contact therewith.

It is to .be noted that in each instance the higher ends of adjacentcells are located on opposite sides of one of the lower contact rolls.The ,upper contact .rolls are l ayspcsitionedin he air space betw en theower-ends of adjac n cells, audit is at suchl wers nds h ttlieelectrolyte is introduced into ,the cells. The distributors 2.1-2.1: i et th fl w f electrolyte p rds f o th lower ends towardthe higher ends ofthe cells. This arrangement'insuresbetter distribution of theelectrolyte, by preventing the electrolyte from concentrating in thelower ends of the cells and overflowing from the lower ends only. Thus,some of the electrolyte may overflow from both ends of each cell.

It is distinctly advantageous to have short individual ll in' r s eparaed by ir sp ces ith the c thod ically charged contact rolls located insuch air spaces, instead of having one continuous, long cell. Obviously,if nonconductive guide rolls were submerged in the electrolyte within asingle cell having one contact. roll at each end and a length equivalentto that of the series of cells provided with many contact rolls, itwould be necessary for the fewer. contactrolls of the single long cellto carry a correspondingly heavier current load to prm duce the sameamount of plating. This wouldvresul-t in making the current density atthe surface of the wires undesirably high in the vicinity of the contactrolls of the single long cell. Although the average current density inthe two systems might remain the same, the distribution of the currentdensity is less uniform when fewer contact rolls are utilized. In themanufacture of a copper-clad steel electrical conductor, the currentdensity at all points along the wire must be carefully controlled,because the current density may critically afiect the crystallinepattern and density of the copper deposit. The nature and density of thecopper deposit have an important bearing on the electrical conductivityand the durability of the completed electrical conductor.

In one practical embodiment of the invention, a horizontal line drawntangent to the bottoms of the upper rolls was about 1 /2 inches below ahorizontal line drawn tangent to the tops of the lower rolls. Allowingfor the depth of the grooves on the rolls, the moving wires change theirelevation 1% inches alternately upwardly and downwardly, each time theyadvance from one contact roll to the next successive roll. In thisembodiment of the invention- 58 cells were used, having an averagelength of about 34 inches each, the distance through the air spacebetween adjacent cells was about 14 inches, and each cell was about 48inches in width. Twentyfive moving wires were successfully electroplatedsimultaneously by this system.

The above-described apparatus is simple in construction and inoperation, and it may be readily disassem- The labor and expense in--plane in which all of the cells have one end mounted,.

means for introducing electrolyte into the lower ends of the cells andfor directing the flow of electrolyte towards the upper-ends of thecells, a plurality of anodically charged plates positioned so as to beimmersed in the electrolyte parallel to and extending along the bottomsof the cells, a plurality of cathodically charged, positivelydrivenrolls mounted rotatably between the cells for electrically contactingand guiding the moving wires, adjacent cells having only one of therolls-mounted between them and successive rolls being positionedalternately above and below the path of the wires contacted so that thewires pass through the cells parallel to the anodes, and let. m ns at bt nds o the ell fo d chargi the. electrolyte therefrom- 2=An appera usfcr e. eet cnlatingv m ingwi c hich prises. a se ies of nd idualquallyspace ls rolytic ll a ign d i t n em s hat a plur li y of wiresmay be. continuously advanced therethrough in parallel, side-by-siderelationship, a plurality of anodically charged plates positioned so asto be immersed in the electrolyte parallel to and extending along thebottoms of the cells, successive cells being alternately inclined atequal anglesin opposite directions so that all of the cells have a lowerend in one horizontal plane and an upper end in. enct cr horiz n l planmea s for i t g c1 trolyte into the lower ends of the cells and fordirecting the flow of electrolyte towards the upper ends of the cells, aplurality of cathodically charged, positivelya driven contact rollsmounted rotatably between the cells and arranged so that adjacent cellshave only one of the rolls mounted between them, each roll beingencircled by a plurality of spaced grooves for guiding the moving wires,successive rolls being, elevated and depressed equal distancesalternately above andbelow the path of the wires contacted, the rollsabove the wires being mounted between the lower ends of adjacent cellsand the rolls below the wires being mounted between the upper ends ofadjacent cells, the bottoms of all of the upper rolls protruding equaldistances slightly below the plane in which the tops of the lower rollslie, so that wires follow a zigzag path through the series of cellsparallel to the anodes, and weirs mounted at both ends of the cells fordischarging the electrolyte therefrom.

3. An apparatus for electroplating moving wires, which comprises aseries of individual, equally spaced, electrolytic cells aligned intandem so that a plurality of wires may be continuously advancedtherethrough in parallel, side-by-side relationship, a plurality ofanodically charged plates positioned so as to be immersed in theelectrolyte parallel to and extending along the bottoms of the cells,successive cells in this series being inclined at equal anglesalternately in opposite directions above a horizontal plane in which allof the cells have one end mounted, means for introducing electrolyteinto the lower ends of the cells and for directing the flow ofelectrolyte towards the upper ends of the cells, a plurality ofcathodic, positively-driven, contact rolls mounted rotatably between thecells and spaced about 48 inches from one another, only one of saidrolls being located between each pair of adjacent cells in the series,successive rolls being alternately elevated and depressed equaldistances above and below the path of the wires, so that the wiresfollow a zigzag path through the series of cells and the wires changetheir elevation about 1% inches alternately upwardly and downwardly eachtime they advance from one contact roll to the next successive roll, andweirs mounted at both ends of each cell for discharging the electrolytetherefrom.

4. Apparatus for electroplating wires, which comprises a series ofelectrolytic cells aligned in tandem, a cathodically charged,positively-driven contact roll mounted between adjacent cells in theseries, one group of alternating rolls being mounted in a firsthorizontal plane and the remaining group of rolls being mounted in adifferenent horizontal plane so that the wires follow a zigzag pathalong the rolls, an anode mounted in each cell parallel to the path ofthe wire through the cell, means at the end of each cell near the lowerend of the anode therein for introducing electrolyte into the cell andfor directing the flow of electrolyte towards the upper end of theanode, and weirs at both ends of the cells for discharging theelectrolyte therefrom.

References Cited in the file of this patent UNITED STATES PATENTS1,065,090 Werth June 17, 1913 2,424,173 Huston 'July 15, 1947 2,490,055HOE Dec. 6, 1949

1. AN APPARATUS FOR ELECTROPLATING MOVING WHICH COMPRISE A SERIES OFELECTROLYTIC CELLS ALIGNED IN TANDEM SO THAT A PLURALITY OF WIRES MAY BECONTINUOUSLY VANCED THERETHROUGH IN PARALLEL, SIDE-BY-SIDE RELATIONSHIP,SUCCESSIVE CELLS IN THE SERIES BEING ALTERNATELY INCLINE AT EQUAL ANGLESIN OPPOSITE DIRECTIONS ABOVE A HORIZONTAL PLANE IN WHICH ALL OF THECELLS HAVE ONE END MOUNTED, MEANS FOR INTRODUCING ELECTROLYTE INTO THELOWER END OF THE CELLS AND FOR DIRECTING THE FLOW OF ELECTROLYTE TOWARDSTHE UPPER ENDS OF THE CELLS, A PLURALITY OF ANODICALLY CHARGED PLATESPOSITION SO AS TO BE IMMERSED IN THE ELECTROLYTE PARALLEL TO ANDEXTENDING ALONG THE BOTTOMS OF THE CELLS, A PLURALITY OF CATHODICALLYCHARGED, POSITIVELYDRIVEN ROLLS MOUNTED ROTATABLY BETWEEN THE CELLS FORELECTRICALLY CONTACTING AND GUIDING THE MOVING WIRES, ADJACENT CELLSHAVING ONLY ONE OF THE ROLLS MOUNTED BETWEEN THEM AND SUCESSIVE ROLLSBEING POSITIONED ALTERNATELY ABOVE AND BELOW THE PATH OF THE WIRESCONTACTED SO THAT THE WIRES PASS THROUGH THE CELLS PARELLEL TO THEANODES, AND OUTLET MEANS AT BOTH ENDS OF THE CELLS FOR DISCHARGING THEELECTROLYTE THEREFROM.